1.Has a heart rate monitor
A heart rate monitor can help show your fitness levels, enabling you to calculate a suitable intensity of exercise.
GPS enables global positioning, useful in map, geo-tagging or navigation apps.
An accelerometer is a sensor used to measure the linear acceleration of a device. A common application is detecting when a device changes between vertical and horizontal positions.
A compass is useful in games, map and navigation software.
This measures barometric air pressure. It can predict weather changes, for example a sudden drop in air pressure could mean a storm is coming. When calibrated correctly it can be used to determine altitude, which helps GPS devices to lock on quicker and with greater accuracy.
A gyroscope is a sensor that tracks the orientation of a device, more specifically by measuring the angular rotational velocity. Initially, they were built using a spinning rotor to detect changes in orientation, like twisting or rotation.